1. Field of the Invention
The present invention relates to a power supply controlling apparatus for a printer, and more particularly, to a power supply controlling apparatus capable of continuing supply of power required to complete printing operation even though a power switch is turned off during printing operation.
The present application is based upon Korean Application No. 97-41631, which is incorporated herein by reference.
2. Description of the Related Art
Referring to FIG. 1, a typical color printer includes a resetting apparatus 15, laser scanning units 16, developing apparatuses 17, a drying apparatus 18 and a transferring apparatus 20 are arranged adjacent to a circulation path of a photosensitive belt 14 circulated by three rollers 11, 12 and 13 and spaced apart from each other by a predetermined distance.
In the process of printing, the laser scanning unit 16 scans light beams over a predetermined region of the photosensitive belt 14 circulating via the resetting apparatus 15. An electrostatic latent image is formed on the photosensitive belt 14 by the scanned light, and the electrostatic latent image is developed by a developer supplied from a developing apparatus 17. A color image is formed on the photosensitive belt 14 by the laser scanning units 16 scanning light beams of various colors and the developing apparatuses 17 developing the scanned image by the developer corresponding to the light beam. The color image formed on the photosensitive belt 14 by a developer is primarily transferred to a transfer roller 21, which rotates partially in contact with the photosensitive belt 14, via the drying apparatus 18. Then, the image formed on the transfer roller 21 is secondarily transferred onto a sheet of paper 23 proceeding forward according to rotation of the transfer roller 21 and a pressure roller 22 which press against each other with the paper 23 therebetween.
Meanwhile, a power switch (not shown) with which a user can interrupt or connect an external commercialized alternating current (AC) power supply with respect to the inside of the printer is typically provided outside the main body. When the power switch is turned off due to a user's mistake or carelessness during a printing operation of the printer, the printing operation is interrupted due to interruption of the power supply. If the power supply is interrupted during the printing operation, the developing material which is not yet transferred to the paper sheet 23 remains on the photosensitive belt 14 or the transfer roller 21, thereby causing contamination of elements. Also, if the contamination is not instantly removed, the printing quality may be severely damaged.